Exogenous gonadotropins--serum oestrogen and progesterone and the effect on endometrial morphology in the rat
Kramer, B.; Stein, B.A.; Van Der Walt, L.A.
Journal of Anatomy 173: 177-186
1990
ISSN/ISBN: 0021-8782 PMID: 2074223 Document Number: 362256
The effect of superovulation, with follicle stimulating hormone and human chorionic gonadotropin, on the endometrium of the rat was investigated prior to (4.5 days), at the time of (5.5 days) and after implantation (6.5 days). In the hyperstimulated groups serum oestradiol levels were significantly higher than in normal pregnant animals at 2.5 and 4.5 days, while progesterone levels were similar in the control and hyperstimulated groups. Consequently the progesterone : oestradiol ratio was significantly lower in the experimental groups prior to implantation. Significant changes in the endometrium caused by the raised oestradiol levels, included an early increase in gland epithelial height, increased surface epithelial height, increased number and length of microvilli, deficiencies in the glycocalyx and decreased mitotic activity in the surface epithelium and stromal cells. In addition, epithelial cell degeneration and failure of decidualisation of stromal cells was observed. These morphological changes adversely effect embryo attachment and implantation and may be an important factor in the low success rate in human in vitro fertilization programmes.